We are not in the era of WoW where any class is John fucking Madden (like Feral druids were), although i am fairly certain that different classes will punish you more if you play incorrectly. Mages for instance have been called faceroll many times over the course of many expansions. The current Fire Mage model could be called faceroll as well since there really are only a few buttons you need to press in order to do DPS, however if you mess up or use your Combustion CD incorrectly or not at the optimal moment you will do far less damage than a mage who does use it correctly.

We are not in the era of WoW where any class is John fucking Madden (like Feral druids were), although i am fairly certain that different classes will punish you more if you play incorrectly. Mages for instance have been called faceroll many times over the course of many expansions. The current Fire Mage model could be called faceroll as well since there really are only a few buttons you need to press in order to do DPS, however if you mess up or use your Combustion CD incorrectly or not at the optimal moment you will do far less damage than a mage who does use it correctly.

^Just for instance.

Uhh feral is still John Madden if you're pushing good dps through trinket procs and DoC

If I were to choose I would say Warlock. I play a Mage and only have one real dot, but the stuff you can do with only that one dot is just insane (if you really want to push it to the maximum). Warlocks have a lot of dots and they need to be managed really good in order to do decent DPS.

I don't think that mage is one of the hardest classes, but it is by no means that easy as "push the button that is highlighted". On the first look it really looks it is. But try to use your infernoblast correctly during bloodlust. Never mess up the normal rotation. Know when you have to move and try to use as less scorches as possible. Use alter time + combustion correctly. Watch procs and use them to the maximum.

Of course every class is as complex. But some guildies were pretty surprised when I told them what you have to have an eye on when you play mage

Affliction warlock. You need to be a master to get the most out of the snapshot dot power mechanic. Every proc, every CD need to be taken in to account for when you should refresh your dot's, put up Haunt etc. There are UI mods though that make this fairly straight forward though.
There is also a certain mechanic you can currently utilize to keep a set of VERY strong dots rolling the entire fight if you play perfectly and the boss fight allows for it. This is why you see some warlocks doing INSANE dps on some fight on world of logs.

What about the different resources? Which one do you guys think is most forgiving and most punishing when handeled wrong or right? Energy, rage or mana?

Runes.

Nobody goes oom anymore, energy and rage are fairly simple. I don't know about Chi. I'm also not sure how they've changed DKs recently but I know for most of their lifespan DKs have had the most complex resource management system.